The invention proceeds from a delivery unit according to the generic type.
DE 10 2008 013 991 A1 has already disclosed a delivery unit, having a drive shaft and a rotor which is driven by the drive shaft and is arranged rotatably in a stator housing, the rotor having a toothing system on its end side which faces away from the drive shaft, which toothing system meshes with a toothing system which is formed on the stator housing, the drive shaft having an oblique sliding plane which interacts with the rotor, is formed on a shoulder of the drive shaft and allows the rotor to tumble with its rotor axis about the drive axis of the drive shaft, working spaces being formed between the toothing system of the rotor and the toothing system of the stator housing, which working spaces can be filled via an inflow and can be emptied via an outflow.
In the first exemplary embodiment, the fluid is fed in axially and is discharged radially. In the second exemplary embodiment, the fluid is fed in and discharged axially. To this end, control valves in the form of nonreturn valves are required. The nonreturn valves cause additional inner leaks, which results in a reduction in the degree of volumetric efficiency of the pump. The valves are additional parts which are associated with additional costs and an increased risk of failure.